Direct C-H magnesiation of thiophenes with an Mg-Mg-bonded compound.

The reaction of the Mg-Mg-bonded compound [K(thf)3]2[LMg-MgL] (1, L = [(2,6-iPr2C6H3)NC(CH3)]22-) with thiophenes afforded magnesium thienyl complexes (2-11) through ortho C-H magnesiation with the release of H2. This provides an efficient approach to metal thienyl reagents, which can be used to construct functionalized thiophenes, e.g., thienyl alcohols from aldehydes or ketones.